Except for an outcrop of the Pierre Formation of the Cretaceous Age in the south central portion of the county, the Ogallala Formation of the Tertiary Age composes the geologic bedrock of Buffalo County. The bedrock becomes progressively deeper front he surface on average as one moves north from the Platte River.
The soil parent materials above the bedrock are loess, alluvium and sand. The most recent deposit is the alluvium on the flood plains along the Platte River. The alluvium generally was washed in from the Loess-Mantled Uplands, but in the Platte River Valley it also includes sand and gravel from outside the area.
Gibbon is situated in the middle of the Platte River Valley, which is fourteen miles wide. This river valley is bordered on either side by a range of sandy hills. The soil is predominantly sandy loam and has a vast supply of water for irrigation. Drainage conditions are good with the major flow of run-off following the Platte River and moving to the southeast.